Ahead of the new series of BGT - which launches next Saturday night - Alesha revealed that the music mogul was really a big softie at heart.
"I know Simon has a reputation as 'Mr Nasty' as a judge, but he's the opposite," Alesha said this week.
She said: "He is a lovely man. I love watching the way he is with the audience and children. He has such a charming way with people and really cares about them."
Alesha and Simon will be joined by Amanda Holden and David Walliams once again on the Britain's Got Talent panel this year, their fifth series together.
"It's always great to be reunited with the gang, because we've worked together for so long, they're like family and it's like being back at school," Alesha said.
Speaking to Closer magazine, Alesha went on to spill on how her daughter Azura and Simon's son Eric had become best pals behind the scenes.
She said: "They're often around each other because we take our children into work some days. They really get on and, last time he saw her, Eric brought her in some toys to play with and a new book.
"He is very sweet, just like his dad."
Britain's Got Talent 2017 launches on Saturday, April 15 at 8PM on ITV.